TNF and infection: In addition, inflammatory processes in the spleen did not seem to account for the rapid development of systemic protection, since no significant differences could be demonstrated between the levels of pro-inflammatory cytokines (TNF-α and IL-6) and Th1 cytokines (IFN-γ, IL-2 and IL-12) at 36, 60 and 72 hours post infection with Kim53ΔJ+P or Kim53pGFP (data not shown).